#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include "dwfcore/Core.h"

#ifdef HAVE_CONFIG_H
#include "dwfcore/config.h"
#endif

#ifdef  DWFCORE_BUILD_ZLIB
#include "dwfcore/zlib/zlib.h"
#else
#include <zconf.h>
#include <zlib.h>
#endif
#include "dwfcore/zip/password.h"

#define local static

#ifdef DYNAMIC_CRC_TABLE

local int crc_table_empty = 1;
local uLongf crc_table[256];
local void make_crc_table OF((void));

/*
  Generate a table for a byte-wise 32-bit CRC calculation on the polynomial:
  x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x+1.

  Polynomials over GF(2) are represented in binary, one bit per coefficient,
  with the lowest powers in the most significant bit.  Then adding polynomials
  is just exclusive-or, and multiplying a polynomial by x is a right shift by
  one.  If we call the above polynomial p, and represent a byte as the
  polynomial q, also with the lowest power in the most significant bit (so the
  byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
  where a mod b means the remainder after dividing a by b.

  This calculation is done using the shift-register method of multiplying and
  taking the remainder.  The register is initialized to zero, and for each
  incoming bit, x^32 is added mod p to the register if the bit is a one (where
  x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
  x (which is shifting right by one and adding x^32 mod p if the bit shifted
  out is a one).  We start with the highest power (least significant bit) of
  q and repeat for all eight bits of q.

  The table is simply the CRC of all possible eight bit values.  This is all
  the information needed to generate CRC's on data a byte at a time for all
  combinations of CRC register values and incoming bytes.
*/
local void make_crc_table()
{
  uLong c;
  int n, k;
  uLong poly;            /* polynomial exclusive-or pattern */
  /* terms of polynomial defining this crc (except x^32): */
  static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

  /* make exclusive-or pattern from polynomial (0xedb88320L) */
  poly = 0L;
  for (n = 0; n < sizeof(p)/sizeof(Byte); n++)
    poly |= 1L << (31 - p[n]);

  for (n = 0; n < 256; n++)
  {
    c = (uLong)n;
    for (k = 0; k < 8; k++)
      c = c & 1 ? poly ^ (c >> 1) : c >> 1;
    crc_table[n] = c;
  }
  crc_table_empty = 0;
}
#else
/* ========================================================================
 * Table of CRC-32's of all single-byte values (made by make_crc_table)
 */
local const uLongf crc_table[256] = {
  0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
  0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
  0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
  0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
  0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
  0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
  0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
  0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
  0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
  0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
  0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
  0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
  0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
  0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
  0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
  0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
  0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
  0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
  0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
  0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
  0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
  0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
  0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
  0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
  0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
  0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
  0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
  0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
  0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
  0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
  0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
  0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
  0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
  0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
  0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
  0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
  0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
  0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
  0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
  0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
  0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
  0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
  0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
  0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
  0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
  0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
  0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
  0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
  0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
  0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
  0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
  0x2d02ef8dL
};
#endif

/* =========================================================================
 * This function can be used by asm versions of crc32()
 */
local const uLongf * _get_crc_table()
{
#ifdef DYNAMIC_CRC_TABLE
  if (crc_table_empty) make_crc_table();
#endif
  return (const uLongf *)crc_table;
}



void ZEXPORT init_keys(const char* password, unsigned long *key)
{
    unsigned int i;
    key[0] = 305419896L;
    key[1] = 591751049L;
    key[2] = 878082192L;

    for (i=0;i<strlen(password);i++)
    {
        update_keys(password[i], key);
    }
}

void update_keys(char ch, unsigned long *key)
{
    char c = ch;
    key[0] = decrypt_crc32(key[0], c);
    key[1] += key[0] & 0xff;
    key[1] = key[1] * 134775813L + 1;
    c = (char)(key[1] >> 24);
    key[2] = decrypt_crc32(key[2], c);
}

char decrypt_byte(unsigned long *key)
{
    int temp = (key[2] & 0xffff) | 2;
    return (char)(((temp * (temp ^ 1)) >> 8) & 0xff);

}

void ZEXPORT decrypt_buffer(char *buffer, unsigned long size, unsigned long *key)
{
    char temp;
    unsigned long i;
    for (i=0;i<size;i++)
    {
        temp = buffer[i] ^ decrypt_byte(key);
        update_keys(temp, key);
        buffer[i] = temp;
    }
}

unsigned long decrypt_crc32(unsigned long l, char c)
{
    const unsigned long *pcrc_table = _get_crc_table();
    return pcrc_table[(l ^ c) & 0xff] ^ (l >> 8);
}


void encrypt_header(long iCrc, char *buf, unsigned long *key)
{
    char c;
    int i, t1;

    srand((unsigned int)(time(NULL)));
    // genereate pseudo-random sequence
    for (i = 0; i < 10; i++)
    {
        t1 = rand();
        c = (char)(t1 >> 6);
        if (!c)
            c = (char)t1;
        c = encrypt_byte(c, key);
        buf[i] = c;

    }
    c = (char)((iCrc >> 16) & 0xff);
    c = encrypt_byte(c, key);
    buf[10] = c;
    c = (char)((iCrc >> 24) & 0xff);
    c = encrypt_byte(c, key);
    buf[11] = c;
}

char encrypt_byte(char c, unsigned long *key)
{
    char t = decrypt_byte(key);
    update_keys(c, key);
    return c ^ t;
}

void encrypt_buffer(char *buf, unsigned long size, unsigned long *key)
{
    unsigned long i;
    for (i=0; i < size; i++)
        buf[i] = encrypt_byte(buf[i], key);
}


//
// PASSWORD SALTING
// ----------------
// The basic idea is to vary the actual input data for the encryption keys
// by changing the password used for initialization which will result in 
// far less similarity in encrypted data across the zip archive.
//
// Step 1 - Append the filename to the password (i.e. salted = password + filename)
// Step 2 - If strlen(salted) > 32, use salted for init_keys(), otherwise:
// Step 3 - Create a new buffer of length len, where n = 1 + ((32 - strlen(salted)) / strlen(filename))
//          rounding down to the floor int.  This will result in a buffer that can hold at least
//          one copy of the original filename.
// Step 4 - Copy the original filename into the new buffer n times.
// Step 5 - XOR the original password once into the new buffer (starting at byte 0)
// Step 6 - Append new buffer to salted (salted' = salted + new buffer), used salted' for init_keys().
//
void dwf_salt_init_keys( const char* filename, const char* password, unsigned long* key )
{
    char* salted = 0;
    size_t plen = strlen( password );
    size_t flen = strlen( filename );
    size_t n = (plen + flen > 32) ? 0 : (1 + ((32 - (plen+flen)) / flen));
    size_t slen = plen + flen + (n*flen) + 1;

    char* next = salted = DWFCORE_ALLOC_MEMORY( char, slen );
    DWFCORE_ZERO_MEMORY( salted, slen );
    DWFCORE_COPY_MEMORY( salted, password, plen );
    next += plen;
    DWFCORE_COPY_MEMORY( next, filename, flen );
    next += flen;

    if (n > 0)
    {
        for (; n>0; n--)
        {
            DWFCORE_COPY_MEMORY( next, filename, flen );
            next += flen;
        }
        
        next = salted + (plen + flen);
        n = min( plen, (slen - (plen + flen + 1)) );

        int i = 0;
        for (; n>0; n--, i++)
        {
            *next++ ^= password[i];
        }
    }

    init_keys( salted, key );

    DWFCORE_FREE_MEMORY( salted );
}



